No speedo, no OD. Stumped

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No speedo, no OD. Stumped

Postby Crossy's son » Tue Aug 04, 2015 4:44 pm

Hey guys long time no hear I know. I picked up a 91.5 W250 automatic and the speedo and the Odo don't work and neither does the overdrive our cruise so I replace the VSS on the transfer case and replace the plug and still nothing I pulled the VSS back off and spend it with a drill with key on and had somebody look at speedo and it does not move however when you're driving down road every once in awhile it will bounce. I need to get this speedo workin. I cant figure this one out. Any help on what to check is appreciated. Im gonna check for 5v at VSS right now

Thanks
Brandon
91.5 W250 5 speed, 500k miles, 3.54's, Powr-Lok, 4" Str8 Exhaust , Egt/Boost on pillar, 435 Injectors, Borgeson Steering shaft, HX35/12wg, 4" lift on 35's, dyno 5/18/13 302hp/792 tq

90 D250 727 3.07's 227k miles
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Re: No speedo, no OD. Stumped

Postby Crossy's son » Tue Aug 04, 2015 4:52 pm

I have 2.7 volts at the orange/white wire at the VSS, and thats with my neg meter lead on the shiny part of the VSS itself, as soon as i plug in the Vss, the voltage drops to 0.
91.5 W250 5 speed, 500k miles, 3.54's, Powr-Lok, 4" Str8 Exhaust , Egt/Boost on pillar, 435 Injectors, Borgeson Steering shaft, HX35/12wg, 4" lift on 35's, dyno 5/18/13 302hp/792 tq

90 D250 727 3.07's 227k miles
Crossy's son
fuel screw!!!!
 
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Re: No speedo, no OD. Stumped

Postby Philip » Mon Aug 17, 2015 6:14 pm

Check the voltage at the wire plug on the left rear of the engine. Also check to se if the wire has rubbed threw going up to that plug.
93 W350 Club/cab w/duals, buckets & console, B&W flatbed, G56, 6 spd, 3:07 rears, gages, HX40/16, 4" exhaust, 6X.018 sticks, rear air ride suspension
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Re: No speedo, no OD. Stumped

Postby Richie O » Sun Aug 23, 2015 2:19 pm

Crossy boy! Hey, I'm never around either. :roll: My 92 has a bad speedo too. My voltage was around 2.7 as well. I assume the vss sensor is just a make and break switch?? Philip buddy, good to see ya on the boards yet again. :D
1989 W250 727, 3.07 L/S, S300, P/S Intercooler, Stans exaust, Pump adjustments, 127k miles,297 hp
1993 W250 extended cab, rag, 4.10 l/s, 6x16's, HTT 62/71/14 piston l/p, Isspro EV series tach, fuel pressure, boost, oil pres, water temp, volt, pryo, 132k/ 301 hp
1992 W250 with NV4500, 3.54's, 16cm 60mm GDS H1C, ground stock cone, Isspro tach, pryo, boost, fuel pressure, slow, rusty, dented,180k
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Re: No speedo, no OD. Stumped

Postby cougar » Sat Aug 29, 2015 11:59 am

Looking at the diagram, what you are describing indicates a lost connection to pin 4 of the PCM which is the sensor return for the VSS and the TPS. Pin 47 supplies a floating voltage for conversion for the VSS only. Besides the connector on the PCM, the black connector at the back of the engine also carries that return line, black/light blue. The VSS is an on/off switch that creates a square wave pulse that the speedo and PCM converts to a timing signal.
RIP 91.5 W250 5 speed. The great experiment.
92 W250 HD 47RH with Compushift. Upgraded H1C to 62/60/16, Scheid Lightning VE, 60# valve springs, DAP 7X.010 injectors, 4" DE exhaust, home made cooler tubes.
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Re: No speedo, no OD. Stumped

Postby peytonmaterne » Wed Dec 09, 2015 3:17 pm

I also have 2.74 volts at the plug, my other truck with working speedo reads 4.99. Not sure what to check next. Crossy, did you get yours working?
91.5, D250, getrag
91.5, D250, auto
84, D150 with 90 dodge/cummins drivetrain
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